Composition for pavements.



parts of either pine-tar or coal-tar.

NITED STATES Patented December 13, 1904;.

EDWARD I. ALLISON, OF SAGINAW, IIIICHIG-A'N.

COMPOSITION FOR PAVEMENTS.

SPECIFICATION forming part of Letters Patent No. 777,173, dated December 13, 1904.

I Application filed December 28, 1903. Serial No. 186,888. (No specimens.)

To (LZ'Z whom it may concern:

Be it known that I, EDWARD I. ALLISON, a citizen of the United States, residing at Saginaw, in the county of Saginaw and State of Michigan, have invented certain new and useful Improvements in Composition for Pavements; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention is a composition of matter to be used for street-pavements and roof-coverings; and the improvement consists in a combination of certain ingredients in proportions stated and the equivalents thereof, as will be more fully set forth in the specification.

The objects of the invention are to provide a hard and durable material not easily abraded and capable of withstanding extreme cold and heat Without cracking or flaking.

In practicing my invention I take oi pulverized shale, such as is commonly procured from coal-mines, eighteen (18) parts and combine with it fifteen (15) parts of sand of medium fineness. This mixture is heated to about the temperature of boiling tar, and to it is added six (6) parts of stone-dust, or in lieu of the stone-dust, where an especially-strong mixture is required, Portland or similar cement. I take oi pine pitch ten (10) parts and mix with it from four (4) to six (6) This mixture is heated until it reaches the boilingpoint and is then thoroughly mixed with the above-specified mixture of shale, sand, and stone-dust or cement.

Since shale from different localities absorbs diiierent amounts of the melted pitch and tar, itis sometimes necessary to increase the abovespecified quantity of the melted mixture that is to be added to the shale, sand, and stone dust. Enough should be added in every case, however, to bring the entire mass to about the consistency of ordinary hot asphalt when laid for paving purposes.

It is found in practice that the pulverized shale imparts resilience and noiseless properties to the pavement and that the melted pinepitch and tar forms a strong and elastic binding between the particles of sand. The binding qualities of the pitch are greatly increased and the cost of the pavement is reduced by mixing the pulverized shale and pitch, thus forming a material which fills the spaces between the particles of sand.

The office of the pine-tar or coal-tar mixed with the pine-pitch is to make a somewhat more fluid binding mixture than the pinepitch alone.

The mixture of pine-pitch and pine-tar in the proportions specified forms a tougher and more durable binder than does the pine-pitch and coal-tar, although the latter mixture is cheaper and may be used in some cases, if desired.

Cement is added for the purpose of making the mixture set quicker and harder; but where the quickness of setting is not of great importance stone-dust may be substituted for the cement. By substituting in this mixture shale in the place of sand a somewhat coarser but softer mixture is obtained, which is found to be a very efiicient paving material when laid between the concrete base and top dressing of an asphalt pavement, forming a slightlyelastic cushion beneath the top dressing.

I/Vhile I have specified in the above mixture fifteen (15) parts of medium-fine sand, I prefer to produce the same result by using nine (9) parts of common river-sand and six (6) parts of line sand, this mixture being equivalent for my purpose to the medium grade of fine sand, which is sometimes diiiicult to procure.

When the mixture is required to set quick but great hardness is not essential-as, for instance, in making sidewalk-blocks I use plaster-of-paris in the above mixture in lieu of cement or stone-dust.

When used for pavements, the material is spread and rolled while hot, the process being practically the same as that now conimonly used in laying ordinary asphalt pavements.

In the manufacture of roof-coverings I presisting of shale, stone-dust, pitch and tar, for the purposes set forth and substantially as described.

In testimony whereof I atfix my signature in presence of two Witnesses.

EDWVARD I. ALLISON.

Vitnesses:

W. I. CATHGART, A. A. EASTERLY. 

